Reveal moldings for exterior plaster are commonly used. A typical molding comprises an extruded aluminum channel with nailing flanges extending laterally outwardly from the base of the channel. The channel sides provide grounds for the plaster on opposite sides with an atractive separation between them. Additionally, the channel forms a trap interrupting transverse water flow and providing a runoff path.
Plaster has a measurable coefficient of thermal expansion. If the stucco or plaster is confined, the resulting stresses will cause the unsightly cracking. The conventional aluminum molding structure is relatively rigid, and does not adequately yield to the thermal stresses. The obvious solution is to provide a molding structure made of thermoplastic material, perhaps with a partial fold or curve in the channel bottom to allow slight movement. However, plastic moldings soon deteriorate when subjected to sunlight.
An object of the present invention is to provide a metal molding for plaster that yields sufficiently to minimize cracking of plaster. Still another object of this invention is to provide a plaster control screed made of metal that oterhwise conforms to the characteristics of traditional plaster screeds.